The invention relates to a special type of display which can be used in those biprogrammed computers in computers capable of having two programs in progress at the same time (also named "biprogrammed computers") in which provision is made for a frequent conversation between the operator and the computer itself (e.g., computers oriented for accounting purposes).
A biprogrammable electronic computer is known in which in the course of each program, a pair of displays each associated with a corresponding program signals the operator with requests for intervention which relate to the relevant program. Moreover, this computer is furnished with a third display for visually displaying the characters introduced by means of the keyboard. Finally, a fourth display is necessary if the computer is oriented for accounting purposes, because programs are typically used which continually require the intervention of the operator for data introduction. Such a request for data is generally accompanied by information on the type of the data; for this purpose, the fourth display is required.
The major disadvantage of this system is that the operator is obliged to converse with a plurality of elements at the same time.
Another disadvantage of this system is due to the error signalling displays as now known in the art. These displays visually display the cause of the request for intervention coded in only two characters; the operator is therefore obliged each time to consult a manual in order to known the operation to be carried out to be able to remove this cause.
Finally, the considerable financial burden arising from the use of so many displays is evident, due to the handling hardware which is required by them.